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Home / DTC / C1228 — Throttle Valve Assembly Mechanical.

C1228 — Throttle Valve Assembly Mechanical.

Detailed page for trouble code C1228.

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Code

C1228

HYUNDAI C — Chassis

Throttle Valve Assembly Mechanical.

Brand: HYUNDAI
Type: C — Chassis
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Carbon build-up or contamination on throttle plate/shaft
  • Foreign object lodged in throttle bore
  • Seized or corroded throttle shaft or linkage
  • Broken/weak return spring or internal mechanical failure in throttle body
  • Damaged or stripped throttle actuator gears
  • Loose or broken mounting/hardware causing misalignment

Symptoms

  • Check Engine Lamp (CEL) or malfunction indicator illuminated
  • Engine enters limp/reduced-power mode or limited throttle
  • Poor throttle response, hesitation or surging
  • Rough or unstable idle; possible stalling at idle
  • Engine will not accelerate normally or pedal feels unresponsive
  • Diagnostic trouble codes related to throttle/accelerator sensors or actuator

What to check

  • Scan for DTCs and freeze frame data; note related throttle/pedal codes
  • Visual inspection of throttle body for carbon, contamination, or debris
  • Inspect throttle body mounting, linkage, and surrounding intake components for interference
  • Check wiring harness and connectors for corrosion, damage, or loose pins
  • Verify battery voltage and inspect relevant fuses/relays before testing actuator
  • Perform a manual throttle plate movement check per service manual (engine OFF) to feel for binding

Signal parameters

  • Throttle position sensor (TPS) voltage: closed ~0.2–1.0 V (varies by model)
  • TPS voltage at wide open throttle: ~4.0–4.8 V (varies by model)
  • Throttle angle reported by ECM/scan tool should change smoothly with throttle command
  • Actuator supply voltage: battery voltage (~12 V) to motor power feed during commanded movement
  • Ground continuity for actuator motor return; very low resistance expected
  • Motor current or load may increase sharply if mechanical binding is present (observed on specialized tools)

Diagnostic algorithm

  1. Connect a capable scan tool, read C1228 and any related codes (P-/C- codes), record freeze-frame and symptoms.
  2. Clear codes and attempt to re-create the fault under controlled conditions (do not force throttle with ignition ON).
  3. Visually inspect throttle body interior for carbon/corrosion, and check for foreign objects or damaged components.
  4. With engine OFF and ignition OFF, manually move throttle plate per service instructions to detect binding or rough spots.
  5. Inspect wiring and connector for the throttle actuator/TPS for corrosion, damaged wires, or poor pins. Wiggle-test while monitoring scan tool values.
  6. With a scan tool, command the throttle actuator and observe throttle plate movement and reported throttle angle/voltage. Compare actual movement to commanded movement.
  7. Measure TPS voltages at connector (key ON, engine OFF) across closed and commanded positions and compare to expected values.
  8. Verify actuator motor power and ground while commanding movement (check for voltage present and ground continuity).
  9. If actuator is powered but plate does not move freely, remove and inspect throttle body for seized shaft, stripped gears, broken spring, or debris. Clean if minor carbon; replace if mechanical damage.
  10. After repair or replacement, perform throttle adaptation/learn procedure with scan tool per manufacturer instructions, then road test and confirm no recurrence.
  11. Safety note: do not force the throttle plate when the actuator is energized. Follow manufacturer service procedures.

Likely causes

  • Throttle plate binding due to carbon deposits
  • Mechanical obstruction (debris or broken part) inside throttle bore
  • Seized throttle shaft or worn bushing
  • Damaged internal actuator gear or spring causing sticking
  • Connector corrosion or partial short causing motor to stall when moving

Fault status

⚠️ Status
C1228 — Throttle valve assembly mechanical fault detected. Throttle plate movement restricted, binding, or internal mechanical failure. Service required to inspect and repair throttle body.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1.0 - 3.0 hours

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371

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